1. Field of the Invention
The present invention generally relates to stabilizer bars found in motor vehicles, and more particularly, to an adjustable stabilizer bar capable of being rapidly adjusted while installed in the motor vehicle.
2. Background of the Invention
It is generally known by automotive designers that torsional stabilizer bars have proven useful in vehicles for many years. Such stabilizer bars commonly employ a transverse torsion bar segment pivotally attached to the vehicle chassis and leading or trailing longitudinal segments attached to a control arm or wheel carrier. These stabilizer bars act in a manner such that when a pair of left and right wheels undergo differential motion in both jounce and rebound travel relative to the vehicle body, tilting of the vehicle body will be resisted by the torsional resistance produced in the stabilizer bar.
For a variety of reasons, automotive designers vary the diameters of conventional stabilizer bars. This diameter change varies the stabilizer bar stiffness, when the diameter is increased it also degrades ride quality in many vehicles. This results because the stabilizer couples the wheels together. For example, when one wheel strikes a raised obstruction in the roadway during straight running, the body will tend to absorb more energy when a stronger or stiffer stabilizer is used than when a bar of lesser torsional stiffness is fitted.
Designers have sought to enhance the function of stabilizer bars in a variety of ways. U.S. Pat. No. 4,648,620 discloses an adjustable stabilizer bar having a base stabilizer bar that can be selectively modified to a higher level of stiffness through a secondary torsional reaction segment engaged by means of a clutch mechanism. This stabilizer cannot produce varied degrees of torsional stiffness, including a zero stiffness condition. U.S. Pat. No. 4,962,943 discloses an automatically adjusting stabilizer bar that relies on a costly and complex control system to hydraulically actuate a pair of cogs disposed between a base stabilizer bar and a torsional outer tube to vary the torsional stiffness of the stabilizer bar. This system is overly complex and does not readily achieve a wide range of torsional stiffness adjustment.
Accordingly, there exists a need, heretofore unfulfilled, for an adjustable stabilizer bar that does not require a costly hydraulic system for adjustment and is capable of being adjusted over a wide range of torsional stiffness, including zero torsional stiffness. This allows for enhanced off road performance in one adjusted position while allowing an operator to tune the stabilizer torsional stiffness for preferred ride quality or handling characteristics during on road vehicle operation.
In accordance with the teachings of the present invention, an adjustable stabilizer bar for a vehicle having a suspension with multiple roadwheels comprises a primary torsional reaction segment having first and second ends and a first end link interconnecting the first end of the primary torsional reaction segment with the suspension. A second end link is provided for interconnecting the second end of the primary torsional reaction segment with the suspension. The second end link is laterally spaced from the first end link when installed in the vehicle such that the primary torsional reaction segment will be torsionally loaded during jounce and rebound motion of the road wheels.
The primary torsional reaction segment includes an outer tube attached to the first end of the primary torsional reaction segment. The outer tube includes a splined inner surface. The primary torsional reaction segment also includes a torsion bar attached to the second end of the primary torsional reaction segment. The torsion bar includes a splined outer surface. An annular region is created between the torsion bar and the outer tube upon assembly. The primary torsional reaction segment also includes a cog disposed in this annular region and it includes inner mating splines for engagement with the splined outer surface of the torsion bar and outer mating splines for engagement with the splined inner surface of the outer tube.
The primary torsional reaction segment includes an actuator operatively engaged with the cog and capable of sliding the cog to a desired position within the annular region such that the cog can be made to transfer all torsional loading between the outer tube and the torsion bar.